Radial engine cam follower



' Nov. 29, 1949 G. D. ANGLE RADIAL ENGINE CAM FOLLOWER 2 Sheets-Sheet 1 Filed Oct. 23, 1946 INVENTOR GZennD. Angle TTORNEYS Nov. 29, 1949 G. D. ANGLE RADIAL ENGINE CAM FOLLOWER 2 Sheets-Sheet 2 Filed Oct. 25, 1946 YLINDER *I INVENTOR GZe/zn D. A rqgle ATTORNEYS CYLINDER CYLINDER CYLINDER CYLINDER Patented Nov. 29, 1949 RADIAL ENGINE CAM FOLLOWER Glenn D. Angle, Thomaston, Conn., assignor to The New Britain Machine Company,

New

Britain, Conn., a corporation of Connecticut Application October 23, 1946, Serial No. 705,188

11 Claims.

My invention relates to improvements in radial engines and in particular to an improved valveoperatin means for such engines.

In the design and manufacture of radial engines, particularly those of five and seven cylinders in the lower power-output bracket, it is desirable to use common or interchangeable parts whenever possible, mainly for purposes of simplicity and reduced cost. Also, it is known that the principal dimensions of a radial engine of a first number of cylinders may permit another engine having more cylinders to be made within the same general space allocations. At least, in designing the first of these engines there need be no sacrifice from a design point of view to provide for the greater number of cylinders, provided use is made of interchangeable parts (or parts having dimensions more or less common to both engine types), such as the crankcase, the cylinders, the pistons, the connecting rods, and the crankshaft.

There are certain parts which cannot be made interchangeable, due to the difference in the number of cylinders. Parts in this category may include the master connecting rod, cams, and certain gears, the purpose or function of which is dictated primarily by the number of cylinders employed. The valve-actuating mechanism including the cam follower is also ordinarily considered to fall in this category of non-interchangeable parts.

This situation with respect to the valve-actuating mechanism may be due to the possible differences in such factors (for both types of engine) as speed of rotation of the cam ring or rings. If a given interval between intake and exhaust-valve operations for one cylinder is to be the same for two engines having different cam-ring speeds, the angle between the camfollower guides must be varied accordingly, for each particular engine design. For example, in a five-cylinder engine in which a single-ring cam may rotate at one-sixth crankshaft speed, the included angle between followers should be 40 degrees in order to provide a total interval of 240 degrees of crankshaft movement between the exhaust and intake openings for any one cylinder. On the other hand, in a seven-cylinder engine in which a single cam ring may rotate at one-eighth crankshaft speed, the included angle would have to be 30 degrees between followers to produce a like sequence for the valves.

It is an object of my invention to provide improved valve-operating means including camfollower mechanisms adaptable to more than one type of radial engine.

It is another object to provide an improved valve-operating mechanism in which the same parts may be employed to provide a first angle between cam followers (with respect to the cylinder served) for a radial engine having a first number of cylinders and a second angl between cam followers for another engine having a different number of cylinders.

It is a more specific object to provide a valveactuator mechanism which permits utilization of the same included angle between longitudinal axes of the inlet and the exhaust followers (with respect to the cylinders served) for both five and seven-cylinder engines.

It is, in general, an object of the invention to provide manufacturers of radial engines with improved mechanisms for increasing the extent of interchangeability of parts between different types of engines, thus reducing manufacturing, tooling, and maintenance costs.

Other objects and various further features of the invention will hereinafter be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings, in which:

Fig. l is a fragmentary end view in partial section of a five-cylinder radial engine incorporating features of the invention;

Fig. 2 is an enlarged partially broken-away view of a portion of the engine of Fig. 1.;

Fig. 3 is a schematic representation illustrative of the cooperation of certain parts in the engine of Fig. 1; and

Fig. 4 is another schematic representation i1- lustrating a similar cooperation of parts in a seven-cylinder radial engine.

Broadly speaking, my invention contemplates provision of equal or nearly equal valve openings for a plurality of types of radial engines by provision of an interchangeable cam follower associated with a valve-actuating mechanism having, for each cylinder served, a single angle between intake and exhaust valve-actuato axes. This single angle is selected preferably approximately midway between the optimum angle between exhaust and intake valve openings for an engine having a first number of cylinders and a corresponding optimum angle for an engine having a second number of cylinders. The cam follower is so related to the valve-actuating mechanism as to provide points of camming contact offset from the valve-actuating axis--the extent of the ofiset being sufficient to define one of the above-mentioned optimum angles between exhaust and intake camming contacts when offset in one direction and the other of said optimum angles when offset in the other direction.

In the specific forms to be described, the cam followers for each cylinder of a five-cylinder engine are turned outwardly so that the outwardly offset points of camming contact subtend a greater included angle than the angle between valve actuating axes. For the case of asevencylinder engine, these same cam followers are turned inwardly so that their inwardly offset points of camming contact subtend a smaller included angle than the angle between axes of the valve-actuating mechanisms. The exact angles between valve actuators and the extent of cam-follower offset are matters of design which may depend upon the rotational speed and nature of the cam, upon the type of engine to which the interchangeable valve-actuator mechanism is to be adapted, and upon. the desired interval of timing between a given operation of an exhaust valve and a corresponding operation of the intake valve associated with thessame cylinder.

,Referringto Figs. 1,2, and 3iof the drawings,

my invention isshownin application to a radial engine having five-cylinders it. Eachcylinder includes an exhaust valveeactuating mechanism H and an intake-valve mechanisml2. In the 'form shown, the valve-actuating mechanisms l !--l2 extend generally radially from the central longitudinal axis'of the engine and include cam followers l3 andld ridingon cam means it: to operate push-rods it. Thecam means l5 may be coupled to the crankshaft ll of the tengine through suitable gear trains ill-49 and-2El--2i, whereby the cam means l5 will rotate at a reduced speed with respect to the crankshaft. The parts which have thus .far been described are well known inthe artand form nopart of my invention.

In accordance with .the invention the-longitudinal. axes of t the .valveeactuating .mechanisms ll and I2 are, for anyone cylinder, inclined with respect to each other atanangleapproximately .midway between the preferred exhaust-intake timing-sequence.interval for a radialengine of a first number of cylinders-andithecorrespond- .ing optimum angle fora second enginehaving a second number of cylinders. In the case illustrated, the valve-actuating mechanism is adaptable interchangeably to a five-cylinder engine and to a seven-cylinder engine. Theangle between the axes of .theactuatingmechanisms H and i2 is therefore intermediate theoptimum timing angles for given'designs ofeach of these types of engines. In the assumed illustrative case, the optimum angle for .the five-cylinder engine is greater than the optimum angle for the seven-cylinder-engine, and in order toapproximate both these optimum-angles with the same angle ofspreadbetween the valve-actuator mechanisms .H and i2, thecam followerslS-M associated therewith includemeans permitting the selective inwardor outward olfsettingof the points of camming contact with respect to the axes of the valve-actuating mechanisms 11-12. In the form shown in Fig.1, .thatis, for afivecylinder radial engine in which the said optimum angle exceeds the compromise angle between Valve-actuating mechanisms l! and G2, the :offsets forthe. cam followers 63 andl i are displaced outwardly with respect to each other and these ing three lobes 22, 23, 2A displaced equally about the periphery of an otherwise circular plate. The

cam ring or plate i5 is driven at one-sixth the rotational speed of the crankshaft. It has been assumed that the desired interval between the exhaust and intake operations within any particular cylinder is 240 degrees of crankshaft rotation. This will mean an optimum angle of 40 degrees between cammed operations of the exhaust and intake valves of a particular cylinder.

In the case .of the seven-cylinder engine schematically illustrated in Fig. 4, another singleplate cam means 25 is provided for actuating allexhaustiand intake valves. The cam 25, in the form shown, includes four lobes 26, 27, 23, 39 spaced equally about the periphery of the other wise circular cam 25, and this cam is driven at one-to-eight reduction with respect to the rota" tional speed of the crankshaft. Thus, in order to maintain the desired exhaust-intake timing interval of 240 degrees of crankshaft rotation the optimum'angle between valve actuations for each cylinder of the assumed seven--cylinder outwardly spread cam-follower elements it? and it may serveto produce an effective timing angle of substantially 40 degreesoptimurn for the assumed case. Also, when these elements are inwardly offset (as shown in Fig. 4) the eifective timing angle may be approximately 30 degrees optimum for the assumed seven-cylinder ease.

I provide means for selectively holding the cam follower in offset position. Fig. 2 shows a preferred means to provide for this selectable offsetting of the cam-follower means it and M. This preferred construction contemplates provision of a pair of oppositely disposed longitudinally extending slots .-ll3l in a guide member 62 for the cam-follower elements. In the form shown .-the cam followercomprises a roller 33 pivotally carried upon a cylindrical member '34, which in turn is longitudinally slidable within the guide member 32. The pivotal support of the roller 33 in the member 34 is oifset from the axis of the member '34 by an amount determined in accordance with the principles discussed above; in the assumed cases, this offset will approximate 2.5 degrees. In the form shown, the displaceable member 34, which may directly actuate the push-rod [6, is formed with a pair of oppositely extending lugs or ears 3535 projecting into and embraced within each of the slots 38-3]. It will be appreciated that with the structure described, it is but a simple operation slidably to remove'the roller 33 and its mount 3 from engagement with the slots SB3l and then to rotate the same degrees prior to reinsertion in the same guide slots. It will be appreciated that the same valve-actuating mechanism and cam follower is thus rendered equally adaptable to a plurality of types of radial engines.

It has been implied that 35 degrees may represent a suitable compromise angle for the case of valve-actuating mechanisms adaptable to either five or'seven-cylinder radial engines. In certain cating valve guides), may be greatly simplified for the five-cylinder engine, in that 36 degrees represents one-tenth of the full 360-degree extent of the engine, and in that there are ten valves to be actuated. This slight departure from the first-suggested compromise angle between the exhaust and intake valve mechanisms for a particular cylinder may result in a slight change in the amount of overlap between successive operations of these valves. Such departures need not be serious, however, if suitable attention is given to design of the cam follower and other elements.

To achieve the interchangeability which has been described it might be argued that symmetry of thrust in cam follower actuation has been sacrificed, with resultant increase in wear, due to the fact that the points of camming contact are offset from the axes of the valve-actuating mechanisms. The side thrust on the inlet and exhaust followers may not be the same during the lift and return periods, and both may be greater than if the points of camming contact fell on the axes of the valve actuating mechanisms. In

actuality, the amount of offset is relatively small,

and it is merely a matter of design of the cam and of the cam follower to reduce the efiect of added thrust.

It will be seen that I have described a relatively simple mechanism which increases the number of parts which may be interchangeable for different types of radial engines having differing numbers of cylinders. The increased interchangeability may result in reduced cost of manufacturing and upkeep for one or more of the .5

types of engine to which the interchangeable parts are adaptable.

While I have described my invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of the invention as defined in the claims which follow.

I claim:

1. In a valve-actuating mechanism for selective application to one of two radial engines having difierent numbers of cylinders, two longitudinally extending valve actuating members including cam followers offset from the longitudinal axes of said members, guide means for each of said valve-actuating members, the angle between said guide means being intermediate an optimum valve-timing angle for one of said engines and an optimum valve-timing angle for the other of said engines, and means cooperating between said guide means and said valve-actuating members for selectably offsetting said cam followers in one of two orientations with respect to the axis of said member, whereby said first optimum angle may be obtained for a first offset orientation and said second optimum angle may be obtained for a second offset orientation.

2. In combination, for application to a first radial engine having a first number of cylinders and to a second radial engine having a second number of cylinders, generally radially directed valve-actuating means including cam-follower means offset from the longitudinal axes of said valve-actuating means, said longitudinal axes being spaced at an angle intermediate an optimum angle between said means for said first engine said second engine, and guide means for said. valve-actuating means, said guide means including means cooperating with said cam-follower; means for holding each of said cam-follower means against angular displacement about thelongitudinal axis of the valve-actuating meanswith which it is associated, whereby the ofisetof said cam-iol1ower means may be retained in a first orientation for use in said first engine and in a second orientation for use in said second engine.

3. In a valve mechanism adaptable to a first radial engine having a first number of cylinders and to a second radial engine having a second number of cylinders, generally radially extending intake and exhaust valve-actuating elements, guide means for said elements for limiting the displacement of said elements to substantially radial motion, the angle between said elements for any particular cylinder being intermediate an optimum angle between such elements for said first radial engine and an optimum angle between such elements for said second radial engine.

4. A valve mechanism according to claim 3, in which said valve-actuating elements include cam-follower means ofiset from the axes of said elements, the included angle of said offset camfollower. means for any particular cylinder being such as to subtend substantially said optimum angle for said first radial engine when the cam followers for any particular cylinder are ofiset outwardly, said included angle subtending substantially said optimum angle for said second radial engine when the cam-followers for a particular cylinder are offset toward each other.

5. A valve mechanism according to claim 3, in which said valve-actuating elements include cam-follower means oliset from the longitudinal axes of said elements, and in which the cam followers for any particular cylinder may be outwardly offset with respect to each other to subtend substantially said optimum angle for the one of said radial engines which has the lesser number of cylinders, and inwardly ofiset toward each other to subtend substantially said optimum angle between such elements for the one of said radial engines which has the greater number of cylinders.

6. A valve mechanism according to claim 3, in which said engines have five and seven cylinders, respectively, and in which the angle between said valve-actuating elements is substantially 35 degrees.

7. In a valve mechanism adaptable to a first radial engine having a first number of cylinders driving a first timing cam through a first reduction coupling and to a second radial engine having a second number of cylinders driving a secondtiming cam through a second reduction coupling, there being a radially extending intake-valve actuator and a radially extending exhaust-valve actuator for each of the cylinders of said engines, whereby for each cylinder of said first engine there is an optimum angle between actuator elements representing a given fraction of the cycle of operation of said first engine, and whereby for each cylinder of said second engine there is a different optimum angle between actuator elements representing the same fraction of the cycle of operation of said second engine, guide means for said valve-actuators, and cam-follower means included with said actuators and ofiset from the longitudinal axes thereof, the

76 angle between said guide means being inter- 7 inedi'ate's'aid first'optimum angle and said second optimum angle.

3. As an article of manufacture, a cam-follower member for selective use in cooperation with a valve actuator in a first radial engine having a first "number of cylinders and in cooperation "with a similar valve actuator in a second radial engine having a second number of cylinders, said camiollower comprising a first portion to engage "one of said valve actuators and to be guided for motion "substantially radially of one of said engines, and a second portion to engage the valve- 'timm eam means of said one engine, the eiiective axes "of said first and said second portions being singularly ofiset from each'other about the central 'eiigi'iie 'axis by an amount substantially equal to one-half the diiierence between an optimum angle from a cylinder axis toa valve-actuating axis for (m at said engines and an optimum angle from 'a cylinder axis to a corresponding valve-actuating axi ro'r the other of said engines, whereby by :offsetting said cam-follower in a first sense said first optimum angle may be obtained for said first engine and by ofisetting said cam-follower inthe opposite sense said. second optimum angle may be obtained 'forsaid second engine.

9. Anarticle of manufacture according to claim 8, in which the angle of ofiset between the effective axes of'saidfirs't'and second portions is substantially 2.5 degrees.

10. In "combination, for application to a first 'r'adial engine having a first number of cylinders and'to a second radial engine having a second number of cylinders,'a"cylinder, valve means in- 'cluding an intake-valve rockerarm and an exhaust-valve rocker arm carried by said cylinder, push-rod -means for said rocker arms and including'selectably ofisettable cam-follower means extending generally radially of the central axis of the engine to which said cylinder is applied, "the angle between axes of said cam-follower means being intermediate 'an optimum angle between 'such elements for said first radial engine and an optimum angle between such elements for said second radial engine.

11. In combination for application to a first radial engine having a first number of cylinders and to 'a second radial engine having a second number of cylinders, a cylinder, a generally radially extending exhaust-valve actuating element, a generally radially extending intake-valve actuating element, the angle between said elements being intermediate an optimum valve-timing angle for one of said engines and an optimum valve-timing angle for the other of said engines, cam-follower means displaceable radially with each of said elements, one of said cam-follower means including means to engage a valve-timing cam at a point offset from the radial axis of the element with which said one cam-follower means is associated.

GLENN D. ANGLE.

REFERENCES CITED fThe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,190,347 Bouicier June 16, 1914 1,254,032 Dietze June 22, 1918 1,591,041 Cutler July 15, 1924 1,670,294 Angle May 22, 1928 1,802,330 Boland Apr. 28, 1931 1,817,645 Poyer 1- Aug. 4, 1 931 FOREIGN PATENTS Number Country Date 140,783 Great Britain June 23, 1921 543,706 France June 9, 1922 696,742 Germany -e. Sept. 27, 1940 

